I actually opened that app for the first time I think since I have been using the IPhone.
Definitely a lot to explore.
While the app is free, as a subscriber to the catalogue which does have some free books you pay about 15 a month for one book credit per month and you use those to get one book a month with that credit.
I am a bibliophile and buy hardback and paperback books, kindle books, nook books and also the last five years Audible books. With ear phones and head phones Audible books are good when you are exercising or stuck places where reading is not that comfortable, like on a riding lawnmower or in the car on long commutes.